Cabinets of the aforesaid kind are known in the art in different structural forms, for example from FR 2 366 430. A rather conventional structural form is disclosed, for instance, in Italian patent No. 1259209, application No. PN92A000024 of Feb. 4, 1992 (corresponding to the publication FR 2 690 195). According to the structural form of this patent, the cabinet is formed of a body having a parallelepiped shape and comprising at least two door wings connected one to the other and arranged to slide in guideways located along a front edge of top and bottom walls of the cabinet body, and along top and bottom walls of a door compartment defined by a side wall of the cabinet body and a vertical partitioning wall inside thereof.
The door wings are foldable from a coplanar closing position to a parallel opening position, and then they are slidable in a concealed position into the door compartment.
One of the door wings, so called “drive wing”, exhibits a vertical side which is connected via hinges to a slide means which is movable along guideways extending in the door compartment along the bottom and top walls of the cabinet body, from a front edge to a rear wall thereof. The other door wing, so called “driven wing”, exhibits a vertical side which is connected via hinges to a slide means which is movable along guideways extending lengthwise the front edges of the top and bottom walls of the cabinet body. The door wings are connected via spring hinges to an intermediate panel provided with an operating handle.
The guideways extending along the bottom and top walls of the door compartment comprise two opposite racks and the slide means of the drive wing include two toothed wheels which mesh with one another on one internal side and are each engaged with one of the racks on the other external side.
In a first phase of movement, the door wings are brought from the closing position, in which they are substantially coplanar, to the opening position, in which the two door wings match one another side by side. In the opening position the slide means of the drive wing are in an extracted position and the slide means of the driven wing are located in suitable receiving housings provided inside the slide means of the drive wing. In these housings, the slide means of the driven wing release spring operated check means providing to hold the slide means of the drive wing in the extracted condition.
In a second phase of movement, the door wings are brought to a concealed position in which both door wings are lead into the door compartment and the intermediate panel contacts the front edge of the cabinet body and closes the door compartment.
Whilst the aforesaid structural form represents one of the most widespread solutions amongst those available in the art, however it exhibits some drawbacks which cause it to be noisy, faulty and poorly reliable in operation.
A first drawback is given by the fact that the movement of the door wings occurs in a discontinuous manner, because it is interrupted between the first and second phase of movement, i.e. at the moment the two door wings are in the folded opening position and they match one another side by side. The interruption is necessary to permit the slide means of the driven wing to move into its receiving housing inside the slide means of the drive wing. In time, however, this operation becomes faulty, mainly because the mechanical parts intended to be mated wear out and because dirt collects on the mechanical parts. Thus, a jamming of the door wing movement mechanism may occur, and therefore maintenance work becomes necessary.
A second drawback of the structural form known in the art is given by the fact that the movement of the door wings into and out of the door compartment is rather noisy, and this is mainly due to the presence of the guide racks extending along the bottom and top walls of the door compartment, as well as to the toothed wheels of the slide means of the drive wing which mesh therewith. Furthermore, it may occur that the toothed wheels, so as to say, “jump” a tooth of a rack; thereby causing the door wings to become misaligned with the door compartment and to be difficult to move.
A third drawback of the known structural form is given by the fact that in order to move the door wings into and out of the concealed position inside the door compartment, the user has to manually operate the operating handle to push and pull the wings, respectively. In fact, according to a known variant of the structural form described above there is provided a linked frame consisting of a pair of crossing arms which are joined pivotally together and to the vertical hinged side of the driving wing and are arranged to slide into the door compartment. The linked frame is provided with an extension spring which retains the arms in a retracted position. Because this spring is loaded when the door wings are pulled out of the door compartment, it is capable of producing a recovery force which is sufficient to cause the door wings to move into the concealed position inside the door compartment, without requiring manual operation by the user.
However, also the operation of this variant is noisy, particularly because of the presence of the linked frame, and the linked frame itself is rather large in size, and therefore, external dimensions of the cabinet being equal, the door wings cannot be entirely moved into the door compartment, but they extend from the front edges of the top and bottom walls of the cabinet body.